Most existing industrial robots face challenges due to their limited intelligence and flexibility, hindering their ability to adapt to complex and dynamic environments. This limitation primarily stems from inadequate exploration of boundary solving within robot workspaces and insufficient analysis of robot singularities. Addressing this gap, this paper introduces a novel method for robot workspace analysis to accurately assess robot singularities. Initially, the paper establishes a kinematics model for a six-axis industrial robot and employs Pieper's solution method to solve inverse kinematics. Subsequently, it integrates geometric and analytical methods to derive the robot workspace surface envelope equation. To further enhance accuracy, the sector space meshing method is applied to discretize the robot workspace across z-direction, radial direction, and rotary angle. Under each spatial mesh point, the robot Jacobi matrix is computed, and the Jacobi condition number is evaluated to determine workspace singularities. Through this proposed methodology, a comprehensive solution for the entire workspace of a six-axis industrial robot is attained, offering substantial support for enhancing industrial robot flexibility.
In the micro-nano structure manufacturing field, large field of view, flexibility, and single exposure are the advantages of laser interference lithography. However, this method can only produce periodic patterns. In this paper, laser interference lithography and optical field modulation techniques are combined. By adjusting the parameters such as the phase and amplitude of the incident light beam, a light field modulation interference model was constructed to study the relationship between the parameters of the incident light beam and the intensity distribution of the interference light field. We verified the feasibility of the method through simulation. Considering the performance of existing optical modulation devices such as the pixel size of spatial light modulators, we discuss the challenges of this approach and the actual resolution that can be achieved. There is no doubt that this provides a new direction for the preparation of multiscale, variable period micro-nano patterns.
KEYWORDS: 3D image processing, 3D metrology, Image processing, Optical testing, Imaging systems, Sensors, Cameras, 3D acquisition, Digital image processing, Calibration
Unlike traditional imaging, the light field imaging can obtain location and direction information by one shot, which makes the dynamic three-dimensional shape measurement possible. Firstly, this paper establishes a pixel light field model, and calibrates the measurement system, which lays the foundation for light field refocus. Then proposes light field 3-D shape measurement method based on digital focus distance measurement and appropriate sharpness evaluation function. Meanwhile, hardware module used in dynamic three-dimensional shape measurement based on light field imaging is designed, which is responsible for real-time collection and processing of the light field images and greatly improves the reconstruction speed of the images. Finally achieve light field 3-D shape measurement. The experimental results are present to demonstrate the feasibility of this technique.
With the improvement of the performance of electro-optical sensors and computer performance, lensless digital in-line holography has been studied and applied widely. However, the resolution of the digital in-line holography system are limited by pixel size and influenced by the twin image. To solve the problem, we proposed a resolution enhancement method, which collects two holograms with different sample-to-sensor distance. The reconstruction is based on Gerchberg–Saxton iteration algorithm, using two normalized and interpolated holograms. We used two prior constraints in the iteration process according to the iteration algorithm for phase retrieval: intensity of the two normalized holograms and the non-negative absorption of the sample. In this method, the interpolation operation before phase retrieval can digitally reduce the sampling interval, and the interpolation point will be optimized with the iteration process. We simulated the resolution enhancement method, and the results of the simulation show that the resolution and image quality of lensless digital in-line holography can be effectively improved.
A method for designing a class of phase-only super-resolving filters with continuous-phase that can be described by a sum of Zernike polynomials with weight coefficients is presented. With the use of the global search algorithm, differential evolution method, and the local search algorithm, the conjugate gradient method, three filters were designed as examples. The main-lobe size of the point spread function of the three filters can be reduced, keeping allowable central intensity and sidelobe intensity for some typical applications. This type of filter has the advantage of lower scatter compared with other phase-only filters composed of discontinuous phase. In particular, such filters can be implemented dynamically by a phase-controlling device.
KEYWORDS: Lithography, Control systems, Semiconducting wafers, Clocks, Photomasks, Process control, Stepper motor drivers, Data communications, Telecommunications, Camera shutters
Three-dimensional wafer stage is an important component of lithography. It is required to high positioning precision and efficiency. The closed-loop positioning control system, that consists of five-phase step motor and grating scale, implements rapid and precision positioning control of the three-dimensional wafer stage. The MCU STC15W4K32S4, which is possession of six independent PWM output channels and the pulse width, period is adjustable, is used to control the three axes. The stepper motor driver and grating scale are subdivided according to the precision of lithography, and grating scale data is transmitted to the computer for display in real time via USB communication. According to the lithography material, mask parameter, incident light intensity, it's able to calculate the speed of Z axis, and then get the value of PWM period based on the mathematical formula of speed and pulse period, finally realize high precision control. Experiments show that the positioning control system of three-dimensional wafer stage can meet the requirement of lithography, the closed-loop system is high stability and precision, strong practicability.
Project lithography has experienced the development of contact, stepper, and step and scan lithography machine. Currently lithography machine has entered the age of twinscan lithography machine. The twinscan lithography machine took advantages of high efficiency and good compatibility, but the focal depth of twinscan lithography machine was only in the nanometer range. In order to guarantee the quality of the exposure, the twinscan lithography machine put forward high request for detecting the map of the wafer surface. Usually, the uniform sampling method and the whole map rebuilding method were used to detect the map of the silicon wafer surface, which is a main cause for the data redundancy. On the other hand, the map reconstructed by this means was not smooth which caused the motor of lithography machine can't response. To avoid these disadvantages, an algorithm for restoring the wafer surface based on B-spline surface reconstruction is proposed in this paper. This method is able to satisfy requirements for the local adaptive refinement, which effectively avoid data redundancy. This method is robust, which means the effect of solving nonlinear problems and inhibiting fuzzy noise is remarkable. The surface reconstructed by this new method is very smooth, which is more suitable for the movement of the motor in lithography machine.
KEYWORDS: Data acquisition, Analog electronics, Data conversion, Lithography, Signal processing, Power supplies, Data storage, Data processing, Error analysis, Digital signal processing
The output signals of the focusing system in lithography are analog. To convert the analog signals into digital ones which are more flexible and stable to process, a desirable data acquisition system is required. The resolution of data acquisition, to some extent, affects the accuracy of focusing. In this article, we first compared performance between the various kinds of analog-to-digital converters (ADC) available on the market at the moment. Combined with the specific requirements (sampling frequency, converting accuracy, numbers of channels etc) and the characteristics (polarization, amplitude range etc) of the analog signals, the model of the ADC to be used as the core chip in our hardware design was determined. On this basis, we chose other chips needed in the hardware circuit that would well match with ADC, then the overall hardware design was obtained. Validation of our data acquisition system was verified through experiments and it can be demonstrated that the system can effectively realize the high resolution conversion of the multi-channel analog signals and give the accurate focusing information in lithography.
Piezoelectric ceramic driving power is one critical technology of achieving the piezoelectric ceramic nano-precision
positioning, which has been widely used in precision manufacturing, optical instruments, aerospace and other fields. In
this paper, piezoelectric ceramic driving power will be summarized on micro-displacement driving technical
development and research. The domestic and overseas piezoelectric-driven ways will be compared and control model
algorithms will be discussed. Describe the advantages and disadvantages of piezoelectric ceramic driving power in a
different driving and control model, and then show the scope of application of driving power.
With the shortening printing wavelength and increasing numerical aperture of lithographic tool, the depth of
focus(DOF) sees a rapidly drop down trend, reach a scale of several hundred nanometers while the repeatable accuracy
of focusing and leveling must be one-tenth of DOF, approximately several dozen nanometers. For this feature, this article
first introduces several focusing technology, Obtained the advantages and disadvantages of various methods by
comparing. Then get the accuracy of dual-grating focusing method through theoretical calculation. And the dual-grating
focusing method based on photoelastic modulation is divided into coarse focusing and precise focusing method to
analyze, establishing image processing model of coarse focusing and photoelastic modulation model of accurate
focusing. Finally, focusing algorithm is simulated with MATLAB. In conclusion dual-grating focusing method shows
high precision, high efficiency and non-contact measurement of the focal plane, meeting the demands of focusing in
193nm projection lithography.
Nanolithography has been investigated by using optical proximity exposure in the evanescent near field in nano-filmed
noble metals. Sub-diffraction-limited feature size can be resolved by using i-line illumination exposure. Compared with
the model of original superlens, we separated the superlens 100nm away from the mask, under the illumination of i-line
light, the initial simulation shows that the sub-diffraction-limited feature as small as 60nm linewidth with 120nm pitch
can be clearly resolved without hard contact between mask and nano-filmed noble metal. By proper design of the
materials and the parameters of nano-filmed layers, better resolution can be realized.
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